MICROACTIVITY TEST (MAT) STUDY OF THE ZSM-5 ADDITION EFFECTS ON FCC PRODUCT YIELDS AND GASOLINE COMPOSITION

A commercial ZSM-5 containing additive was tested at a MAT unit and th e derived results concerning product distribution as well as gasoline composition shifts have been interpreted by means of changes in the ra tes of certain secondary reactions occurring during catalytic cracking . The most important results of the ZSM-5 addition are gasoline yield decrease, LPG alkenes increase and RON gain. The gasoline composition changes include a significant decrease of the C6-C-9 alkanes yield, li ghter gasoline formation through increase of the C5 hydrocarbons yield s, increased branching in the light alkenes and a small decrease in th e naphthenes and aromatics yields. Most of the above effects have been interpreted by taking into account the enhanced alkenes reactivity on ZSM-5. A comparison of the present results with those from pilot plan ts and commercial units reveal that the shifts imposed by ZSM-5 either to the product yield distribution or to gasoline composition are in v ery good agreement, despite the significant differences of the absolut e yields.